1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, and more particularly, to a photoreceptor medium cleaning device and a method of preventing print quality from being degraded due to a developer which remains on an outer surface of a photoreceptor medium.
2. Description of the Related Art
Generally, an electrophotographic image forming apparatus forms a latent electrostatic image on a photoreceptor medium such as a photoreceptor drum or photoreceptor belt, develops the latent electrostatic image with toner of predetermined colors, and transfers the latent electrostatic image to print paper to form a predetermined image.
A conventional wet electrophotographic image forming apparatus includes a development unit which applies a developer to a latent electrostatic image, which is formed on the photoreceptor medium by a laser scanning unit (LSU), to form a desired image on the photoreceptor medium, a transfer unit which transfers the image to the print paper, and a fusing and fixing unit which fuses and fixes the transferred image onto the print paper.
The development unit includes a developer roller which faces the photoreceptor medium and rotates with its part in the developer that is contained in a developer container receiving the developer from a cartridge storing the developer.
The predetermined image, which is developed on an outer surface of the photoreceptor medium by transferring the developer from the developer roller to the photoreceptor medium, is transferred to the print paper by the transfer unit.
Here, the image formed on the outer surface of the photoreceptor medium is not completely transferred to the print paper by the transfer unit but partially remains on the outer surface of the photoreceptor medium. Since the remaining image disturbs the formation of another latent electrostatic image on the developer roller, it must be eliminated. Usually, it is eliminated from the photoreceptor medium by a cleaning blade installed near the photoreceptor medium. The cleaning blade directly contacts the outer surface of the photoreceptor medium and clears the remaining image off the outer surface. The direct contact between the cleaning blade and the outer surface of the photoreceptor medium causes the photoreceptor medium and the cleaning blade to be worn away, a cleaning efficiency of the cleaning blade is degraded, and maintenance of the photoreceptor medium and the cleaning blade becomes difficult.
Moreover, since it is difficult to maintain a uniform contact between the cleaning blade and the photoreceptor medium, the remaining image may not be satisfactorily, completely or sufficiently eliminated, and a durability of the parts decreases, resulting in an increase in cost.
Particularly, in a case where a high-concentration developer (of about 30-60%) is used, when the cleaning blade contacts the outer surface of the photoreceptor medium before the remaining image on the outer surface is completely dried, toner particles permeate the surface of the cleaning blade made of, for example, polyurethane, having a lower hardness than the photoreceptor medium and adhere thereto, thereby decreasing the cleaning efficiency.